Soluble azo dyestuffs



Patented Jan. 17, 1939 PATENT OFFICE SOLUBLE Azonynsrurrs Mordecai Mendoza and George fStuart James White, Blackley, Manchester,-England, assignms to Imperial Chemical Industries Limited, a :.corporation of Great Britain No Drawing. :Application June a, 1937, Serial No. 146,314. In Great Britain June 4, 1936 7 Claims.

This invention relates to the, manufacture of new azo dyestuffs and their application in the dyeing of furs, pelts, hair and the like materials; and especially to soluble azo dyestuffs made by coupling diazotized 4-amino-4'-nitro-dipheny1- amine-2-sulfonic acid with a class of amino naphthol compounds. a

It is among the objects of the invention to provide new azo dyestuffs which are soluble in water. Another object of the invention is to provide dyes which can be used to dye furs, hair animal fibres and the like to give dyeings of level shades having good fastness to rubbing. Another object of the invention is to provide processes for preparing the new dyestuiis. Other objects of the invention will be apparent from the following description.

According to the invention we manufacture new dyestufis by coupling diazotized .4-amino-4'-nitrodiphenylamine-Z-sulphonic acid with an aminonaphthol devoid of sulphonic or carboxylic groups or with an N-substituted derivative there- As N-substituted coupling components we may use, for example, N-alkyl, N-hydroxyalkyl, N-aryl or N-acylamino-naphthols.

Also according to the invention new and valuable colorings are produced on furs, pelts, hair and the like materials by dyeing with the said new dyestuiis.

The new dyestuffs of the present invention are soluble in water. They have good affinity for fur on which they give valuable level shades of good fastness to rubbing.

Furs, pelts, hair or the like materials which are to be dyed according to the invention may previously besubmitted to the so-called killing process, that is treatment with alkaline agents such as soda ash, ammonia, lime or caustic soda in order to degrease and purify the materials and make them more receptive of the dyestuffs to be applied. Where such killing process is to be followed by a chrome tannage treatment it is desirable first to remove from the materials any residual alkali remaining from the said killing process. This may conveniently be done by rinsingthe materials in a weakly acid bath.

It is advantageous to subject the furs or pelts before dyeing to a treatment (for example, the so-called chrome tannage process) with agents which enable the cutaneous portions to withstand the effect of moderately raised dyeing temperatures. Such agents are, for example, chrome alum, alkali-bichroniates and basic chromium sulphate. As is well known, furs or pelts which have been submitted to such chrome tannage processes, tend to become strongly acid during wet storage. ,It is advantageous to neutralize this acidity, for example, with sodium bicar-v bonate, to approximately pH 6 to pH 7 before commencing the dyeing operation. In the case of freshly chrcme tanned pelts neutralization is not generally necessary.

The furs, pelts, hairs and the like may be submitted, if desired, to a further pre-treatment with agents which increase the dyeing capacity of the hairy portions and promote even dyeing. Among such agents are hypochlorites, as in the so-called chlorinating process, orphosphates.

' It is preferred to commence the dyeing process -I.

under approximately neutral conditions and subsequently to complete the exhaustion of the dyebath by addition of acids such as acetic or formic acids. If desired, inorganic salts, buifering agents, wetting or dispersing agents, may be added to the dyebath. The choice of dyeing temperature is dependent on thematerials to be dyed, and the effect desired. When it is desired to obtain a homogeneous shade on unshorn furs which still retain the horny guard hairs, a dyeing temperature of approximately '75-80 C. is to be preferred. .In the case of shorn furs or pelts lower dyeing temperatures, for example, -60 C., may conveniently be used to obtain homogeneous shades. Lower dyeing temperatures than those indicated may be used but at temperatures below 40 C. there is an increasing tendency for a larger proportion of dye-stuiT to be taken up preferentially by the cutaneous parts of the fur or pelt. At temperatures higher than 80 C. the possibility of damage to the cutaneous parts is increased.

The colorings obtained according to the invention are characterized by solidity and evenness of shade and good fastness to light and rubbing.

. The invention is illustrated but not limited by the following examples in which the parts are by.

weight.

. Example 1 30.9 parts of 4-nitro-4'-aminodiphenylamine- 2-sulphonic acid are dissolved in 400 parts of water containing 5.3 parts of anhydrous sodium carbonate and to the solution are added 6.9 parts of sodium nitrite. The mixture is heated to 45 C. and while stirring at this temperature 25.2 parts of concentrated hydrochloric acid (36%;) diluted with parts of water are slowly added. Stirring is continued until diazotization is complete and the diazo suspension is then cooled to below 10 C. The'cooleddiazo suspension is then stirred into an ice-cold solution of 15.9 parts of 1,5-amino- SOaNa Example 2 A solution of 15.9 parts of 1,5-aminonaphthol in'300 parts of water containing 10.1 parts of concentrated hydrochloric acid (36%) is stirred into acooled (10 C.) diazo suspension obtained as described in Example 1. Stirring is continued until coupling is complete (6-8 hours) when sufiicient caustic soda solution is added to the resulting acid suspension of the dyestufi to make the coupling mixture alkaline to litmus paper. The temperature is raised to 50 0., common salt is added to precipitate the new dyestuff which is then filtered off, dried and powdered. The new dyestufi is soluble in water and dyes fur in violet shades of good fastness to rubbing.

The compound is represented by the formula:

' 110- Ozl I-C NHN=N NH2 s ozNa Example 3 By using instead of the coupling component of Example 1 the same amount of 2,7-aminonaphthol, there is obtained, with similar procedure, a

new dyestuif which dyes fur in reddish shades.

The compound is represented by the formula:

ITIH2 soaNa Example 4 100 parts (damp weight) of long-haired, chrome-tanned white rabbit fur are entered at 40 G. into a dyebath consisting of 1 part of the dyestufi of Example 1 dissolved in 3000 parts of water. The temperature of the dyebath is raised to 75 C. during minutes and after minutes at this temperature 1 to 1.5 parts of glacial acetic acid are added, followed, after a further interval of 30 minutes, by 0.5 part of 80 %E aqueousformic acid. Dyeing is then continued'for a further 40 minutes at 75 C., the dyed fur is then removed, dried and drummed in hardwood. sawdust for 2 to 4 hours. The resulting fur is colored on the under wool, the guard hairs and the skin in a brown shade of good fastness to rubbing.

tanned'white rabbit fur are entered at 40 C. into The coupling mixture,

' rubbing.

Further examples of dyestuffs obtainable according to the invention are given in the following table:

Coupling component Coupling medium Shade on fur l-dimethylamino-fi-naphthol Alkaline to litmus-.. Brown. l-acetylamino-S-naphtho1 ..do Violet. l-acetylaminoJ-paphthol l do Red-violet 2-phcnylamlno-7-naphthol- .do Red.

1 B hydroxyethylamino 5- do Brown naphthol.

As many variations of the invention will be apparent to those skilled in the art and can be made without departing from the spirit and scope of the invention, it is to be understood no limitations are intended in the annexed claims except such asare specifically recited or are imposed by the prior art.

We claim:

1. The compounds represented by the formula in which X is one of the group consisting of amino, phenylamino, di-alkylamino, hydroxyalkylamino and acylamino.

2. A compound represented by the formula S OaNa 3. The compound represented by the formula CH3 CH3 SOaNa 4. The compound produced by coupling 4- nitro-l'-amino-diphenylamine-2-sulphonio acid in alkaline coupling medium with l-p-hydroxyethylami-no-5naphthol.

5. A dye obtainable by coupling diazotized 4- am'ino-l-nitro-diphenyl-amine' 2 sulfonic acid to an azo dye coupling component of the group consisting of amino naphthols in which the amino and-hydroxy groups are in the 1-5, 1-7 and 2-7 positions respectively, and the'amino group is one of the group consisting of amino, hydroxyalkylamino, dialkyl-amino, acylamino; and phenylamino.

6. The process which comprises adding a mixture containing diazotized 4-amino-4'-nitro-dipheny1amine-2'-su1phonic acid to an alkaline mixture containing 1,5 aminonaphthol, and maintaining the coupling mixture alkaline until coupling is completed.

The process which comprises adding a mixture containing diazotized 4-amino-4-nitro-diphenylamine-2'-sulphonic acid to an acid mixture containing 1,5-aminonaphthol, and maintaining the coupling mixture acid until coupling is completed and then making the mixture alkaline to litmus.

MORDECAI MENDOZA. GEORGE STUART JAMES WHITE. 

